1. Field of the Invention
This invention relates to pushbutton type tuners for radio receivers and more directly to means of improving the interaction of the gears in the tuning assembly and simplifying the installation of the treadle bar mechanism in the tuner.
2. Prior Art
The treadle bar drive gear and the treadle bar gear of pushbutton type tuners are conventionally biased into a meshed position by some form of linkage. Previous linkage mechanisms have been subject to backlash problems combined with gear slippage. Attempts to solve these twin problems have typically used a fixed lug or pin near the end of each of two lever arms as pivot points and a biasing spring connecting the opposite ends of the two lever arms to cause the lever arms to apply pressure on the mounting shafts of the two gears. These attempts have proven inadequate for satisfactory alignment of the treadle bar drive gear and treadle bar gear without an assembly line adjustment which required an adjustment pivot screw and lock nut. Even with a factory adjustment, the gears did not necessarily stay aligned because of the "scissors" type action of the linkages. The backlash problem still remained to be solved.